An evaluation of models for partitioning eddy covariance-measured net ecosystem exchange into photosynthesis and respiration
An evaluation of models for partitioning eddy covariance-measured net ecosystem exchange into photosynthesis and respiration
复制标题
DOI：
10.1016/j.agrformet.2006.09.001
复制
发表时间：
2006-12
影响因子：
6.2
通讯作者：
P. Stoy;G. Katul;M. Siqueira;J. Juang;K. Novick;Joshua M. Uebelherr;R. Oren
中科院分区：
文献类型：
--
作者：
P. Stoy;G. Katul;M. Siqueira;J. Juang;K. Novick;Joshua M. Uebelherr;R. Oren
我们利用涡动协方差(EC)技术连续4年测量了北卡罗来纳州杜克森林毗邻的老农田(OF)、人工松林(PP)和阔叶林(HW)生态系统的净生态系统CO2交换(NEE)。为了计算NEE及其组成部分--总生态系统生产力(GEP)和生态系统呼吸(RE)--的年度总和，对不同的“通量分配”模型(FPM)进行了测试，并将所得到的C通量估计值与C预算方法、反向模型、基于生理学的正向模型、室内呼吸测量以及基于Sap通量和蒸散测量的同化限制的公布估计值进行了比较。我们的分析表明，更复杂的FPM，特别是“非矩形双曲线法”，始终产生最合理的C通量估计。在使用夜间数据估计RE的FPM中，一种在短时间内对指数模型进行参数化的模型产生的预测更接近于预期的通量值。为了探索FPM向数据注入了多少“新信息”，我们使用了形式信息论方法，并计算了以下信息的Shannon熵：(1)概率密度，用于评估通量测量分布的变化；(2)小波能量谱，用于评估NEE时间序列内内部自相关性的变化。基于这一联合分析，空位填充对白天数据的IC影响不大，但空位填充显著改变了夜间数据在概率域和小波谱域中的变化。
We measured net ecosystem CO2exchange (NEE) using the eddy covariance (EC) technique for 4 years at adjoining old field (OF), planted pine (PP) and hardwood forest (HW) ecosystems in the Duke Forest, NC. To compute annual sums of NEE and its components – gross ecosystem productivity (GEP) and ecosystem respiration (RE) – different ‘flux partitioning’ models (FPMs) were tested and the resulting C flux estimates were compared against published estimates from C budgeting approaches, inverse models, physiology-based forward models, chamber respiration measurements, and constraints on assimilation based on sapflux and evapotranspiration measurements. Our analyses demonstrate that the more complex FPMs, particularly the ‘non-rectangular hyperbolic method’, consistently produced the most reasonable C flux estimates. Of the FPMs that use nighttime data to estimate RE, one that parameterized an exponential model over short time periods generated predictions that were closer to expected flux values. To explore how much ‘new information’ was injected into the data by the FPMs, we used formal information theory methods and computed the Shannon entropy for: (1) the probability density, to assess alterations to the flux measurement distributions, and (2) the wavelet energy spectra, to assess alterations to the internal autocorrelation within the NEE time series. Based on this joint analysis, gap-filling had little impact on the IC of daytime data, but gap-filling significantly altered nighttime data in both the probability and wavelet spectral domains.